This invention relates to voltage regulators such as used with television deflection circuits.
Circuit arrangements frequently used in television receivers combine switched mode power supplies (SMPS) with transistor horizontal deflection. Various types of SMPS circuits have been used; many have a common feature of providing a regulated DC supply to the horizontal deflection circuit. The horizontal deflection circuit, however, draws an AC current from the power supply. By avoiding the necessity of providing a regulated DC input voltage, a substantial saving in circuit costs and a substantial increase in circuit efficiency may be obtained.
Conventional switched mode transformers for television receiver application are of the flyback or backwards converter type, require a relatively close coupling, have critical tolerances, and are relatively expensive to manufacture. In a commonly used switched mode system using a backwards converter with transistor regulator switch, the AC voltage at the secondary side of the switched mode transformer is rectified and filtered by a capacitor. The DC voltage across the filter capacitor provides the input supply voltage for the horizontal output stage. It would be desirable to omit such a separate rectifying step.
Other regulator circuits include a flyback transformer primary winding coupled to a regulator switch, the horizontal deflection winding, retrace capacitor, and trace switch being coupled to a flyback secondary winding. A capacitor tunes with the flyback transformer for energy transfer to the deflection circuit. In such circuits, however, the conduction time of the regulator switch cannot be selected independent of the tuning requirements for the flyback transformer.